All U.S. patents cited within this specification are hereby incorporated by reference.
Wax-based and/or oil-based ink and ink-jet systems require compatible colorants therein to provide the most effective and reliable printing results. Derivatives of poly(oxyalkylenated) dyes and/or colorants are particularly desired for these end-uses because of their miscibility, high color strength characteristics, as well as ease in handling liquid colorants of this nature. The hydroxyl groups of such poly(oxyalkylenated) colorants and/or dyes are susceptible to adventitious attack by Lewis acids and bases present within the reaction medium. Unfortunately, such an attack renders the colorant unreactive, and incapable of modifications designed to tailor wax- and/or oil-solubility or compatibility. Such unreactive, residual species are generally present as impurities in the desired colorants. Such unwanted reaction products create undesirable possibilities of reduced colorant solubilities, viscosity modifications, weakening of color strengths, and other like problems, such as discussed within certain prior art references, including U.S. Pat. No. 5,782,966 to Bui et al., and U.S. Pat. No. 5,637,638 to Chandler et al., as well as European Patent Application 769,509 to Banning et al. Such references indicate the problems associated with typical prior art processes for manufacturing certain dyes (including wax-based ink types) and/or colorants. Thus, removal or, more importantly, avoidance of ways to generate these unreactive species is absolutely necessary for providing reliable and effective dyes and/or colorants for such end-use applications. These prior art references illustrate ways to tailor the desired physical properties via the reaction of isocyanate with the dyes and/or colorants themselves after formation of such compounds. Unfortunately, such a reaction modifies the colorants as long as they are reactive. It has no effect on colorants that have been rendered unreactive. Such a synthetic route would therefore always produce unwanted unreactive impurities that are detrimental to the performance of these products in the desired ink systems. A more reliable process and thus a more reliable dye and/or colorant compound is thus necessary to provide the industry with a high color strength, optimum viscosity, high purity dye and/or colorant, particularly within wax-based and/or oil-based ink applications. The prior art teachings have not provided a sufficiently consistent soluble wax-based dye and/or colorant due to these adventitious reaction problems. The costs involved in purification necessary to ensure the finished dye and/or colorant is viable and not off-quality have proven excessive enough to merit the need for even greater improvements within this technological field.
Examples of polyoxyalkylene substituted colorants include those taught within U.S. Pat. No. 5,919,839, and EP 0 896 038 A2 describe phase change, or hot melt inks utilizing the reaction product of an isocyanate (e.g., octadecyl isocyanate) and hydroxyl containing colorant to form a colored urethane wax. Other examples of such reactions include U.S. Pat. No. 5,919,846 and PCT patent Application WO 94/14902 (all describing the reaction of hydroxyl containing colorants with mono and diisocyanates). These colorants, in order to be utilized within such hot melt ink systems require high purity and complete compatibility within the wax-based ink system. The presence of electrophilic species, in this case, phthalates for example, in the urethane substituted xanthene colorants reduces the compatibility of these colorants in such wax based ink systems. U.S. Pat. No. 4,833,197 describes an offset ink using diluents, for example, mineral oils with a boiling range of 200°-350° C., and no more than 20% of aromatic components. Again, however, electrophilic phthalates present within the urethane-substituted xanthene colorants remain insoluble in these diluents, thus making these colorants unsuitable for use in these applications. Such a problem is inherent as well with other electrophiles.
Thus, even though poly(oxyalkylenated) dyes and/or colorants have only recently been made available to the wax-based ink market, the utilization of such colorants, particularly made from certain poly(oxyalkylenated) intermediates and other reactants, has still been limited due to the lack of complete compatibility in wax and/or oil based systems due to the formation of the aforementioned deleteroius electrophile-hydroxyl reaction products. There thus exists a need to improve upon this procedure and ultimately to produce a novel intermediate which provides the ability of forming highly desirable derivatized oxyalkylenated dyes and/or colorants but does not require a multi-step process in forming the intermediate alone which furthermore precludes the formation of deleterious phthalates. To date, the prior art has not accorded such an improvement within this specific area of colorant chemistry. Because of the lack of such a specific type of dye and/or colorant intermediate, the versatility and widespread use of such colorants in different types of inks and substrates has not been available. There is thus a need to provide wax-based and/or oil-based ink-jet colorants and compositions that are readily and consistently soluble due to reduction of electrophilic reaction products. To date, there have been no improvements for such wax-based dyes and/or colorants reducing the possible production of deleterious electrophile impurities thus permitting consistent use within, as one possible end-use, wax-based ink-jet inks.